Clinical Impact of KIR2DS3 and KIR2DL3 Genes in Neuroblastoma Patients.

OBJECTIVE: Neuroblastoma is a common fatal tumor of childhood. Natural killer (NK) cells can exert direct cytotoxicity on tumor cells. The killer immunoglobulin-like receptor (KIR) family of NK cell receptors is involved in activation/inhibition of NK cells. In the KIR gene cluster, six of them (3DS1, 2DS1-5) encode receptors triggering activation, while seven of them (3DL1-3, 2DL1-3, 2DL5) encode receptors triggering inhibition. We aimed to assess the distribution of genetic polymorphisms of KIRs on the clinical course of neuroblastoma and provide guidance on potential therapeutic options. METHODS: Our study group included 50 neuroblastoma patients and 100 healthy children as controls. Twenty-eight patients were boys, and twenty-two were girls; median age was 36 months. Fourteen patients had stage 1, 2, 3, or 4S disease, and 36 patients had stage 4 disease. Isolated DNA from the peripheral blood was amplified for sequence-specific oligonucleotide probe analysis of 16 KIR genes. The Fisher's exact test was used to evaluate the variation of KIR gene distribution. RESULTS: All patients had a lower frequency of KIR2DS3 compared to the control group (p = 0.005). Evaluation of individual KIR genes/genotypes in patients with early stages (stage 1, 2, 3, and 4S) versus stage 4 disease revealed that the frequency of KIR2DS3 was increased in early stages (p = 0.023). Inhibitory KIR2DL3 was increased in the patient group compared to controls (p = 0.038). Furthermore, the frequency of KIR2DL3 was higher in stage 4 neuroblastoma patients compared to the patients with early stages (p = 0.023). CONCLUSION: Our data suggest a role for KIR2DS3 and KIR2DL3 in development of neuroblastoma. Thus, modulation of KIR2SD3 and/or KIR2DL3 expression or function might present a novel therapeutic strategy for neuroblastoma.

Increased Susceptibility of the CD57- NK Cells Expressing KIR2DL2/3 and NKG2C to iCasp9 Gene Retroviral Transduction and the Relationships with Proliferative Potential, Activation Degree, and Death Induction Response.

Nowadays, the use of genetically modified NK cells is a promising strategy for cancer immunotherapy. The additional insertion of genes capable of inducing cell suicide allows for the timely elimination of the modified NK cells. Different subsets of the heterogenic NK cell population may differ in proliferative potential, in susceptibility to genetic viral transduction, and to the subsequent induction of cell death. The CD57-NKG2C+ NK cells are of special interest as potential candidates for therapeutic usage due to their high proliferative potential and certain features of adaptive NK cells. In this study, CD57- NK cell subsets differing in KIR2DL2/3 and NKG2C expression were transduced with the iCasp9 suicide gene. The highest transduction efficacy was observed in the KIR2DL2/3+NKG2C+ NK cell subset, which demonstrated an increased proliferative potential with prolonged cultivation. The increased transduction efficiency of the cell cultures was associated with the higher expression level of the HLA-DR activation marker. Among the iCasp9-transduced subsets, KIR2DL2/3+ cells had the weakest response to the apoptosis induction by the chemical inductor of dimerization (CID). Thus, KIR2DL2/3+NKG2C+ NK cells showed an increased susceptibility to the iCasp9 retroviral transduction, which was associated with higher proliferative potential and activation status. However, the complete elimination of these cells with CID is impeded.

Significance of inhibitory maternal killer-cell immunoglobulin-like receptor (KIR) and fetal KIR ligand genotype combinations in placenta related obstetric complications.

Some maternal killer-cell immunoglobulin-like receptor (KIR) and fetal KIR ligand genotypes are associated with obstetric complications, such as recurrent miscarriage, fetal growth restriction, preeclampsia, and preterm birth. However, how KIR/KIR ligand genotypes affect these placenta-related obstetric complications has not been fully understood. We aimed to demonstrate the association of maternal KIR-fetal KIR ligand genotype combinations with immunological/metabolic risk factor associated placenta-related obstetric complications. This study consisted of three groups of pregnant women: 1) Miscarriage group (n = 30), 2) Complicated Pregnancy (CP) group (n = 30), and 3) Control group (n = 30). The observed maternal genotype frequencies of all inhibitory and activating KIRs were similar in all groups (p > 0.05). However, inhibitory 2DL3 was quite frequent in the miscarriage group (p = 0.052). There was no difference between groups in terms of centromeric and telomeric maternal haplotypes (p > 0.05). The fetal group 1 HLA-C genotype was frequently detected in the miscarriage and CP groups with rates of 83.3 % and 93.3 % respectively, while the observed frequency was 70 % in the control group. The fetal group 2 HLA-C genotype was the same in all groups. The results demonstrated significantly less fetal group 2 HLA-C homozygosity in the CP groups when compared to the control group (p = 0.020). The fetal HLA-Bw4 genotype was detected more frequently in the miscarriage and CP groups (p = 0.028 and p = 0.001, respectively). The inhibitory KIR/KIR ligand genotype combinations of 2DL3-C1 and 3DL1-Bw4 were more frequent in the miscarriage and CP groups (p = 0.045 and p = 0.002, respectively). Enhanced NK cell inhibition may be one of the mechanisms underlying placenta-related obstetric complications.

Missing Self-Induced Microvascular Rejection of Kidney Allografts: A Population-Based Study.

BACKGROUND: Circulating anti-HLA donor-specific antibodies (HLA-DSA) are often absent in kidney transplant recipients with microvascular inflammation (MVI). Missing self, the inability of donor endothelial cells to provide HLA I-mediated signals to inhibitory killer cell Ig-like receptors (KIRs) on recipient natural killer cells, can cause endothelial damage in vitro, and has been associated with HLA-DSA-negative MVI. However, missing self's clinical importance as a nonhumoral trigger of allograft rejection remains unclear. METHODS: In a population-based study of 924 consecutive kidney transplantations between March 2004 and February 2013, we performed high-resolution donor and recipient HLA typing and recipient KIR genotyping. Missing self was defined as the absence of A3/A11, Bw4, C1, or C2 donor genotype, with the presence of the corresponding educated recipient inhibitory KIR gene. RESULTS: We identified missing self in 399 of 924 transplantations. Co-occurrence of missing self types had an additive effect in increasing MVI risk, with a threshold at two concurrent types (hazard ratio [HR], 1.78; 95% confidence interval [95% CI], 1.26 to 2.53), independent of HLA-DSA (HR, 5.65; 95% CI, 4.01 to 7.96). Missing self and lesions of cellular rejection were not associated. No HLA-DSAs were detectable in 146 of 222 recipients with MVI; 28 of the 146 had at least two missing self types. Missing self associated with transplant glomerulopathy after MVI (HR, 2.51; 95% CI, 1.12 to 5.62), although allograft survival was better than with HLA-DSA-associated MVI. CONCLUSION: Missing self specifically and cumulatively increases MVI risk after kidney transplantation, independent of HLA-DSA. Systematic evaluation of missing self improves understanding of HLA-DSA-negative MVI and might be relevant for improved diagnostic classification and patient risk stratification.

Influence of HLA-C environment on the spontaneous clearance of hepatitis C in European HIV-HCV co-infected individuals.

Natural killer (NK) cell functions are regulated by diverse inhibitory and activating receptors, including killer cell immunoglobulin-like receptors (KIR), which interact with human leukocyte antigen (HLA) class I molecules. Some KIR/HLA genetic combinations were reported associated with spontaneous clearance (SC) of hepatitis C virus (HCV) but with discordant results, possibly reflecting KIR and/or HLA gene polymorphism according to populations. KIR/HLA genetic combinations associated with both an exhaustive NK and T cell repertoire were investigated in a cohort of HIV-HCV co-infected individuals with either SC (n = 68) or chronic infection (CI, n = 163) compared to uninfected blood donors [controls (Ctrl), n = 100]. Multivariate analysis showed that the HLA C2C2 environment was associated with SC only in European HIV-HCV co-infected individuals [odds ratio (OR) = 4·30, 95% confidence interval = 1·57-12·25, P = 0·005]. KIR2D+ NK cell repertoire and potential of degranulation of KIR2DL1/S1+ NK cells were similar in the SC European cohort compared to uninfected individuals. In contrast, decreased frequencies of KIR2DS1+ and KIR2DL2+ NK cells were detected in the CI group of Europeans compared to SC and a decreased frequency of KIR2DL1/S1+ NK cells compared to controls. Regarding T cells, higher frequencies of DNAX accessory molecule-1 (DNAM-1)+ and CD57+ T cells were observed in SC in comparison to controls. Interestingly, SC subjects emphasized increased frequencies of KIR2DL2/L3/S2+ T cells compared to CI subjects. Our study underlines that the C2 environment may activate efficient KIR2DL1+ NK cells in a viral context and maintain a KIR2DL2/L3/S2+ mature T cell response in the absence of KIR2DL2 engagement with its cognate ligands in SC group of HCV-HIV co-infected European patients.

Arsenite suppresses IL-2-dependent tumoricidal activities of natural killer cells.

Chronic exposure to arsenic causes cancers in various organs including the skin, liver, lung, and bladder in humans, but the mechanisms of the multi-organ carcinogenicity of arsenic remain unknown. Natural killer (NK) cells play important roles in the immune surveillance and elimination of tumor cells. Although accumulating evidence has indicated that arsenic has immunosuppressive properties, little is known about the effects of arsenic on the tumoricidal functions of NK cells. We examined the effects of arsenite on the cytotoxic activities of human and mouse NK cells toward target tumor cells. Exposure of human NK-92 cells and primary mouse NK cells to sublethal doses of arsenite reduced the IL-2-activated cytotoxic activities toward human K562 cells and murine YAC-1 cells, respectively. NK cells recognize target cells via integrated signals from both activating and inhibitory receptors and induce apoptosis of target cells via a granzyme/perforin system. We found that exposure of NK-92 cells to arsenite diminished the IL-2-activated down-regulation of the inhibitory receptors, KIR2DL2 and KIR2DL3, and the up-regulation of granzyme B and lymphotoxin-α. The IL-2-activated increases in secretion of interferon-γ and IL-10 were also slightly reduced by arsenite. Thus, arsenite suppressed the IL-2-activated cytotoxic activity of NK cells by disrupting multiple pathways required for the recognition and killing of target tumor cells. Our findings provide new insights into the roles of NK cell-mediated tumor immunity in cancer development by arsenic.

Natural killer cell receptor variants and chronic hepatitis B virus infection in the Vietnamese population.

OBJECTIVES: Genes of host immunity play an important role in disease pathogenesis and are determinants of clinical courses of infections, including hepatitis B virus (HBV). Killer-cell immunoglobulin-like receptor (KIR), expressed on the surface of natural killer cells (NK), regulate NK cell cytotoxicity by interacting with human leukocyte antigen (HLA) class I molecules and are candidates for influencing the course of HBV. This study evaluated whether variations in KIR gene content and HLA-C ligands are associated with HBV and with the development of liver cirrhosis and hepatocellular carcinoma. METHODS: A Vietnamese study cohort (HBV n = 511; controls n = 140) was genotyped using multiplex sequence-specific polymerase chain reaction (PCR-SSP) followed by melting curve analysis. RESULTS: The presence of the functional allelic group of KIR2DS4 was associated with an increased risk of chronic HBV (OR = 1.86, pcorr = 0.02), while KIR2DL2+HLA-C1 (OR = 0.62, pcorr = 0.04) and KIR2DL3+HLA-C1 (OR = 0.48, pcorr = 0.04) were associated with a decreased risk. The pair KIR2DL3+HLA-C1 was associated with liver cirrhosis (OR = 0.40, pcorr = 0.01). The presence of five or more activating KIR variants was associated with hepatocellular carcinoma (OR = 0.53, pcorr = 0.04). CONCLUSIONS: KIR gene content variation and combinations KIR-HLA influence the outcome of HBV infection.

The immunoglobulin γ marker 17 allotype and KIR/HLA genes prevent the development of chronic hepatitis B in humans.

Hepatitis B virus (HBV) infection causes a self-limiting disease in most individuals. However, < 10% of infected subjects develop a chronic disease. Genetic host variability of polymorphic genes at the interface of innate and acquired immunity, such as killer immunoglobulin-like receptors (KIR), their human leucocyte antigen (HLA) and IgG allotypes (GM), could explain this different clinical picture. We previously showed a protective role of the KIR2DL3 gene for the development of chronic hepatitis B (CHB), and a detrimental role of the KIR ligand groups, HLA-A-Bw4 and HLA-C2. We have expanded the previous analysis genotyping patients for GM23 and GM3/17 allotypes. The comparison of the patients with CHB with those who resolved HBV infection showed that the presence of GM17 allele virtually eliminated the risk of developing CHB (OR, 0·03; 95% CI, 0·004-0·16; P < 0·0001). In addition, the combination of GM17, KIR2DL3, HLA-A-Bw4 and HLA-C2 was highly sensitive to predict the outcome of HBV infection.

Imbalance of Genes Encoding Natural Killer Immunoglobulin-Like Receptors and Human Leukocyte Antigen in Patients With Biliary Cancer.

BACKGROUND & AIMS: Bile duct tumors are rare and have poor prognoses. Natural killer (NK) cells are frequent in human liver and infiltrate these tumors but do not control their progression. Responses of NK cells are regulated by NK immunoglobulin-like receptors (KIRs), which interact with HLA class I ligands. We aimed to characterize the features of the KIR gene loci and their ligands in patients with bile duct cancer (BDC). METHODS: We performed combined multidimensional characterization of genes that encode KIRs and their ligands in blood samples from patients with BDC from Sweden, followed for up to 8 years after diagnosis (n = 148), in 2 geographically matched cohorts of healthy individuals from Northern Europe (n = 204 and n = 900), and in healthy individuals from 6 geographically unrelated populations (n = 2917). We used real-time polymerase chain reaction, RNA sequencing, immunohistochemistry, and flow cytometry to evaluate NK-cell presence, as well as KIR and KIR-ligand expression in bile duct tumors and control tissues. RESULTS: Patients with bile duct tumors had multiple alterations at the KIR gene loci. KIR loci are grouped into genotypes that encode more inhibitory (group A) and more activating (group B) receptors, which can be subdivided into centromeric and telomeric fragments. Patients with BDC had a lower prevalence of KIR2DL3, which was linked to disequilibrium in centromeric A/B and B/B genotypes, compared with control individuals. The associations between KIRs and KIR ligands differed between patients with BDC and control individuals; patients had an altered balance between activating and inhibitory KIRs. KIR-positive NK cells infiltrated biliary tumors that expressed matched KIR ligands. CONCLUSIONS: In a multidimensional analysis of DNA from blood samples of patients with BDC in Europe, we found patients to have multiple alterations at the KIR and HLA gene loci compared with control individuals. These alterations might affect NK-cell tumor surveillance. NK cells from bile duct tumors expressed KIRs and were found in tumors that expressed cognate ligands. This should be considered in development of immune-based therapies for BDC.

A novel antibody combination to identify KIR2DS2high natural killer cells in KIR2DL3/L2/S2 heterozygous donors.

The killer cell immunoglobulin-like receptor (KIR) KIR2DS2 induces natural killer (NK) cell activation upon ligation and in genetic studies is associated with protection against certain cancers and viral infections. One of the difficulties in understanding KIR2DS2 has been that ligands have been hard to define. In part, this is because the high sequence homology between KIR2DS2 and KIR2DL3/KIR2DL2 has made it difficult to make antibodies that specifically detect NK cells expressing KIR2DS2. Using transfected NK cell line (NKL) cells and primary human samples, we report the identification of a novel antibody combination which allows identification of NK cells with relatively high expression of KIR2DS2. This separation is sufficient to examine primary human NK cell activation in response to KIR2DS2 specific ligands.

Impact of HLA Allele-KIR Pairs on HIV Clinical Outcome in South Africa.

BACKGROUND: HLA class I contributes to HIV immune control through antigen presentation to cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. In contrast to investigations of CTL, studies of NK cells in HIV control through HLA-killer immunoglobulin-like receptor (KIR) interactions remain sparse in African cohorts. METHODS: Treatment-naive, chronically HIV-infected adults (N = 312) were recruited from South Africa, and the effects of HLA-KIR pairs on clinical outcome were analyzed. RESULTS: There was no significant difference in viral load among all subjects with HLA alleles from the HLA-C1 group (P = .1). However, differences in HLA-C type significantly influenced viremia among 247 KIR2DL3 positives (P = .04), suggesting that specific HLA-KIR interactions contribute to immune control. Higher viral load (P = .02) and lower CD4+ T-cell counts (P = .008) were observed in subjects with HLA-C*16:01+KIR2DL3+. Longitudinal analysis showed more rapid progression to AIDS among HLA-C*16:01+KIR2DL3+ subjects (adjusted hazard ratio 1.9, P = .03) than those without this genotype, independent of CD4+ T-cell count and viral load. CONCLUSIONS: These results highlight the existence of unique anti-HIV innate immunity within distinct populations and the contribution of KIR on NK cells and some CTLs to the well-described HLA-mediated impact on HIV disease progression.

Novel multiplex PCR-SSP method for centromeric KIR allele discrimination.

Allelic diversity of the KIR2DL receptors drive differential expression and ligand-binding affinities that impact natural killer cell function and patient outcomes for diverse cancers. We have developed a global intermediate resolution amplification-refractory mutation system (ARMS) PCR-SSP method for distinguishing functionally relevant subgroups of the KIR2DL receptors, as defined by phylogenetic study of the protein sequences. Use of the ARMS design makes the method reliable and usable as a kit, with all reactions utilizing the same conditions. Six reactions define six subgroups of KIR2DL1; four reactions define three subgroups of KIR2DL2; and five reactions define four subgroups of KIR2DL3. Using KIR allele data from a cohort of 426 European-Americans, we identified the most common KIR2DL subtypes and developed the high-throughput PCR-based methodology, which was validated on a separate cohort of 260 healthy donors. Linkage disequilibrium analysis between the different KIR2DL alleles revealed that seven allelic combinations represent more than 95% of the observed population genotypes for KIR2DL1/L2/L3. In summary, our findings enable rapid typing of the most common KIR2DL receptor subtypes, allowing more accurate prediction of co-inheritance and providing a useful tool for the discrimination of observed differences in surface expression and effector function among NK cells exhibiting disparate KIR2DL allotypes.

KIR2DL3 and the KIR ligand groups HLA-A-Bw4 and HLA-C2 predict the outcome of hepatitis B virus infection.

Killer immunoglobulin-like receptors (KIRs) regulate the activation of natural killer cells through their interaction with human leucocyte antigens (HLA). KIR and HLA loci are highly polymorphic, and certain HLA-KIR combinations have been found to protect against viral infections. In this study, we analysed whether the KIR/HLA repertoire may influence the course of hepatitis B virus (HBV) infection. Fifty-seven subjects with chronic hepatitis B (CHB), 44 subjects with resolved HBV infection and 60 healthy uninfected controls (HC) were genotyped for KIR and their HLA ligands. The frequency of the HLA-A-Bw4 ligand group was higher in CHB (58%) than subjects with resolved infection (23%) (crude OR, 4.67; P<.001) and HC (10%) (crude OR, 12.38; P<.001). Similar results were obtained for the HLA-C2 ligand group, more frequent in CHB (84%), than subjects with resolved infection (70%) (crude OR, 2.24; P<.10) and HC (60%) (crude OR, 3.56; P<.01). Conversely, the frequency of KIR2DL3 was lower in CHB (81%) than in subjects with resolved infection (98%) (crude OR, 0.10; P<.05). These results suggest a detrimental role of HLA-A-Bw4 and HLA-C2 groups, which are associated with the development of CHB, and a protective role of KIR2DL3. A stepwise variable selection procedure, based on multiple logistic regression analysis, identified these three predictive variables as the most relevant, featuring high specificity (90.9%) and positive predictive value (87.5%) for the development of CHB. Our results suggest that a combination of KIR/HLA gene/alleles is able to predict the outcome of HBV infection.

Resurrecting KIR2DP1: A Key Intermediate in the Evolution of Human Inhibitory NK Cell Receptors That Recognize HLA-C.

KIR2DP1 is an inactive member of the human lineage III KIR family, which includes all HLA-C-specific receptor genes. The lethal, and only, defect in KIR2DP1 is a nucleotide deletion in codon 88. Fixed in modern humans, the deletion is also in archaic human genomes. KIR2DP1 is polymorphic, with dimorphism at specificity-determining position 44. By repairing the deletion, we resurrected 11 alleles of KIR2DP1F , the functional antecedent of KIR2DP1 We demonstrate how K44-KIR2DP1F with lysine 44 recognized C1+HLA-C, whereas T44-KIR2DP1F recognized C2+HLA-C. Dimorphisms at 12 other KIR2DP1F residues modulate receptor avidity or signaling. KIR2DP1 and KIR2DL1 are neighbors in the centromeric KIR region and are in tight linkage disequilibrium. Like KIR2DL1, KIR2DP1 contributed to CenA and CenB KIR haplotype differences. Encoded on CenA, C1-specific K44-KIR2DP1F were stronger receptors than the attenuated C2-specific T44-KIR2DP1F encoded on CenB The last common ancestor of humans and chimpanzees had diverse lineage III KIR that passed on to chimpanzees but not to humans. Early humans inherited activating KIR2DS4 and an inhibitory lineage III KIR, likely encoding a C1-specific receptor. The latter spawned the modern family of HLA-C receptors. KIR2DP1F has properties consistent with KIR2DP1F having been the founder gene. The first KIR2DP1F alleles encoded K44-C1 receptors; subsequently KIR2DP1F alleles encoding T44-C2 receptors evolved. The emergence of dedicated KIR2DL2/3 and KIR2DL1 genes encoding C1 and C2 receptors, respectively, could have led to obsolescence of KIR2DP1F Alternatively, pathogen subversion caused its demise. Preservation of KIR2DP1F functional polymorphism was a side effect of fixation of the deletion in KIR2DP1F by micro gene conversion.

Ocular toxoplasmosis: susceptibility in respect to the genes encoding the KIR receptors and their HLA class I ligands.

The objective of this study was to investigate the influence of the genes encoding the KIR receptors and their HLA ligands in the susceptibility of ocular toxoplasmosis. A total of 297 patients serologically-diagnosed with toxoplasmosis were selected and stratified according to the presence (n = 148) or absence (n = 149) of ocular scars/lesions due to toxoplasmosis. The group of patients with scars/lesions was further subdivided into two groups according to the type of ocular manifestation observed: primary (n = 120) or recurrent (n = 28). Genotyping was performed by PCR-SSOP. Statistical analyses were conducted using the Chi-square test, and odds ratio with a 95% confidence interval was also calculated to evaluate the risk association. The activating KIR3DS1 gene was associated with increased susceptibility for ocular toxoplasmosis. The activating KIR together with their HLA ligands (KIR3DS1-Bw4-80Ile and KIR2DS1+/C2++ KIR3DS1+/Bw4-80Ile+) were associated with increased susceptibility for ocular toxoplasmosis and its clinical manifestations. KIR-HLA inhibitory pairs -KIR2DL3/2DL3-C1/C1 and KIR2DL3/2DL3-C1- were associated with decreased susceptibility for ocular toxoplasmosis and its clinical forms, while the KIR3DS1-/KIR3DL1+/Bw4-80Ile+ combination was associated as a protective factor against the development of ocular toxoplasmosis and, in particular, against recurrent manifestations. Our data demonstrate that activating and inhibitory KIR genes may influence the development of ocular toxoplasmosis.

The differential impact of natural killer (NK) cell education via KIR2DL3 and KIR3DL1 on CCL4 secretion in the context of in-vitro HIV infection.

Carriage of certain inhibitory natural killer (NK) cell receptor (iNKR)/HLA ligand pairs is associated with protection from infection and slow time to AIDS implicating NK cells in HIV control. NK cells acquire functional potential through education, which requires the engagement of iNKRs by their human leucocyte antigen (HLA) ligands. HIV infection down-regulates cell surface HLA-A/B, but not HLA-C/E. We investigated how NK cell populations expressing combinations of the iNKRs NKG2A, KIR2DL3 (2DL3) and KIR3DL1 (3DL1) responded to autologous HIV infected CD4 (iCD4) cells. Purified NK cells from HIV-uninfected individuals were stimulated with autologous HIV iCD4 or uninfected CD4 T cells. Using flow cytometry we gated on each of the 8 NKG2A+/- 2DL3+/- 3DL1+/- populations and analysed all possible combinations of interferon (IFN)-γ, CCL4 and CD107a functional subsets responding to iCD4 cells. Infected CD4 cells induced differential frequencies of NKG2A+/- 2DL3+/- 3DL1+/- populations with total IFN-γ+ , CCL4+ and CD107a+ functional profiles. 2DL3+ NKG2A+ NK cells had a higher frequency of responses to iCD4 than other populations studied. A higher frequency of 2DL3+ NK cells responded to iCD4 from individuals that were not HLA-C1 homozygotes. These results show that 2DL3+ NK cells are mediators of HIV-specific responses. Furthermore, responses of NK cell populations to iCD4 are influenced not only by NK cell education through specific KIR/HLA pairs, but also by differential HIV-mediated changes in HLA expression.

A multifaceted computational report on the variants effect on KIR2DL3 and IFNL3 candidate gene in HCV clearance.

HCV infection causes acute and chronic liver diseases including, cirrhosis and hepatocellular carcinoma. Following HCV infection, spontaneous clearance occurs in approximately 20 % of the population dependant upon HCV genotype. In this study, functional and non-functional variant analysis was executed for the classical and the latest HCV clearance candidate genes namely, KIR2DL3 and IFNL3. Initially, the functional effects of non-synonymous SNPs were assigned on exposing to homology based tools, SIFT, PolyPhen-2 and PROVEAN. Further, UTR and splice sites variants were scanned for the gene expression and regulation changes. Subsequently, the haplotype and CNV were also identified. The mutation H77Y of KIR2DL3 and R157Q, H156Y, S63L, R157W, F179V, H128R, T101M, R180C, and F176I of IFNL3 results in conservation, RMSD, total energy, stability, and secondary structures revealed a negative impact on the structural fitness. UTRscan and the splice site result indicate functional change, which may affect gene regulation and expression. The graphical display of selected population shows alleles like rs270779, rs2296370, rs10423751, rs12982559, rs9797797, and rs35987710 of KIR2DL3 and rs12972991, rs12980275, rs4803217, rs8109886, and rs8099917 of IFNL3 are in high LD with a measure of [Formula: see text] broadcasting its protective effect in HCV clearance. Similarly, CNV report suggests major DNA fragment loss that could have a profound impact on the gene expression affecting the overall phenotype. This roundup report specifies the effect of NK cell receptor, KIR2DL3 and IFNL3 variants that can have a better prospect in GWAS and immunogenetic studies leading to better understanding of HCV clearance and progression.

Siglec-7 Defines a Highly Functional Natural Killer Cell Subset and Inhibits Cell-Mediated Activities.

Sialic acid-binding immunoglobulin-like lectin-7 (Siglec-7) is an inhibitory receptor expressed on natural killer (NK) cells. In this study, we investigated the relationship between Siglec-7 expression and NK cell functions. Siglec-7 was highly expressed on NK cells and was preferentially expressed by mature NK cells from peripheral blood of healthy adults. Siglec-7(+) NK cells displayed higher levels of activating receptors CD38, CD16, DNAM1, NKp30 and NKp46, but lower levels of inhibitory receptors such as NKG2A and CD158b, compared with Siglec-7(-) NK cells. Functional tests showed that Siglec-7(+) NK cells displayed more CD107a degranulation and IFN-γ production than Siglec-7(-) NK cells. Siglec-7 inhibited NK cell functions when interacting with specific antibodies. These data suggest that Siglec-7 defines a highly functional NK cell subset and suppresses NK cell-mediated functions when cross-linked with specific antibodies.

KIR2DL2/2DL3-E(35) alleles are functionally stronger than -Q(35) alleles.

KIR2DL2 and KIR2DL3 segregate as alleles of a single locus in the centromeric motif of the killer cell immunoglobulin-like receptor (KIR) gene family. Although KIR2DL2/L3 polymorphism is known to be associated with many human diseases and is an important factor for donor selection in allogeneic hematopoietic stem cell transplantation, the molecular determinant of functional diversity among various alleles is unclear. In this study we found that KIR2DL2/L3 with glutamic acid at position 35 (E(35)) are functionally stronger than those with glutamine at the same position (Q(35)). Cytotoxicity assay showed that NK cells from HLA-C1 positive donors with KIR2DL2/L3-E(35) could kill more target cells lacking their ligands than NK cells with the weaker -Q(35) alleles, indicating better licensing of KIR2DL2/L3(+) NK cells with the stronger alleles. Molecular modeling analysis reveals that the glutamic acid, which is negatively charged, interacts with positively charged histidine located at position 55, thereby stabilizing KIR2DL2/L3 dimer and reducing entropy loss when KIR2DL2/3 binds to HLA-C ligand. The results of this study will be important for future studies of KIR2DL2/L3-associated diseases as well as for donor selection in allogeneic stem cell transplantation.

The investigation of killer cell immunoglobulin-like receptor genotyping in patients with systemic lupus erytematosus and systemic sclerosis.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterised by the production of autoantibodies and the involvement of multiple organ systems. Systemic sclerosis (SSc) is another autoimmune disease that causes fibrosis. We will aim to analyse the role of killer cell immunoglobulin-like receptor (KIR) genotypes and their existence with the respective HLA ligands in patients with SLE and SSc. Forty-five SLE, 25 SSc and 40 healthy controls were included. We examined the presence/absence of KIR2DL1, 2DL2, 2DL3, 2DL4, 2DL5A, 2DL5B, 2DS1, 2DS1, 2DS2, 2DS3, 2DS4, 2DS5, 3DL1, 3DL2, 3DL3, 3DS1, 2DP1, 3DP1 and their known HLA ligands. In the SLE group, the KIR2DL5, KIR2DL5B and KIR2DS3 genes were significantly more frequent, and KIR2DL3 gene was significantly less than in controls (p values <0.05). In SSc patients, the KIR2DS3 gene was more frequent than in controls (p = 0.032). The KIR2DL3 gene was detected more frequently in controls while KIR2DS3 gene was more frequent in the patient group when SLE and SSc patients were combined (p values < 0.05). The KIR2DS2/HLA-C and KIR2DS2/HLA-C combinations were significantly more in both SLE and SSc groups than in controls. The KIR2DL2 and KIR2DL5B genes were protective from neurologic involvement in SLE patients (p values <0.05). The variations of some KIR genes such as KIR2DL5, KIR2DL5B, KIR2DS3 and KIR2DL3 may have a role in the pathogenesis of SLE and SSc. Also, the presence of KIR2DL2 and KIR2DL5B may cause major organ involvement, like neurologic involvement, in SLE.